Vulnerability identifier: #VU83521

Vulnerability risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-4398

CWE-ID: CWE-190

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
ATP series
Hardware solutions / Routers for home users
USG FLEX series
Client/Desktop applications / Antivirus software/Personal firewalls
VPN series
Client/Desktop applications / Antivirus software/Personal firewalls
USG FLEX 50W
Hardware solutions / Firmware
USG20W-VPN
Hardware solutions / Firmware

Vendor: ZyXEL Communications Corp.

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to integer overflow in the source code of the QuickSec IPSec toolkit used in the VPN feature. A remote attacker can pass specially crafted data to the application, trigger integer overflow and cause a denial of service condition on the target system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

ATP series: 4.32 - 5.37

USG FLEX series: 4.50 - 5.37

USG FLEX 50W: 4.16 - 5.37

USG20W-VPN: 4.16 - 5.37

VPN series: 4.30 - 5.37

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External links
http://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-vulnerabilities-in-firewalls-and-aps

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.